Normalization and uncertainty effects in three objective tasks
using first-order and second-order textures

Vision Sciences Society (2004), abstract #E56, page 134

A contrast-gain control (normalization) has been demonstrated by
having observers subjectively rate the perceived texture segregation
of element-arrangement textures from constant-difference series
of such textures (Graham and Sutter, 2000). Here the perception of
these textures is investigated using three objective tasks: (A) Region
Segregation -- Identifying the orientation of a rectangular region of
an element-arrangement texture embedded in a background of another; (B)
Texture Identification -- Identifying the orientation of the stripes
in a striped element-arrangement texture; (C) Texture Detection (in
Certain and Uncertain conditions) -- Detecting the presence of a striped
element-arrangement texture.

Each texture was composed of two types of element. The two types
differed in contrast but were identical in spatial characteristics
(either a Gabor patch or a Gaussian blob). The two types were arranged
either to form a striped- or a checkerboard-arrangement texture.

Observers' did much less well on the region segregation task than
on the other two tasks. Nonetheless, the signature of normalization
was seen in all three tasks.

The detection and identification results using Gabor-element
textures demonstrated two properties of second-order (complex) channels
previously shown for first-order channels. (1) The relationship between
identification and detection can be explained by the existence of channels
that are independent of one another. In the case of these second-order
patterns, the independent sets of channels are second-order (complex)
channels sensitive to the vertical and to the horizontal striped- element
arrangements respectively. (2) The amount by which observers do better
when certain than uncertain can be explained by assuming that on each
trial observers can ignore any channels that they know will not give
useful information (sometimes referred to as "excluding distracters").